Hitherto, jet blast walls that have been installed in airports have been made of steel. Such blast wall structures exhibit significant strength so as to withstand jet blasts from departing jet aircraft, particularly as they run up the engines at the end of the runway just prior to departure. However, steel blast wall structures have a number of drawbacks, including the fact that they must be continually maintained such as by cleaning and painting, they are specifically subject to corrosion and therefore have a relatively short finite life, and because they are made of steel they exhibit conductive and magnetic characteristics which may be unacceptable to radio and/or radar installations at the airport or signals from approaching or departing aircraft.
This latter drawback may mean the placement of a jet blast wall structure in inconvenient or inappropriate location; or it may mean that radio and/or radar installations, particularly such as antennae arrays, radio beacon installations, radio frequency localizer installations, and the like, may have to be placed at locations that are less efficient and/or more difficult to access.
Still further, in the unlikely event of impact of an aircraft with a steel jet blast wall structure, significant damage may occur to the nose cone, wingtip, or other part of the impacting aircraft.
Yet another drawback of steel jet blast wall structures is the requirement for the use of cranes or the like during their installation and/or repair. The presence of cranes on or near airport runways may require that the runway be shut down to aircraft traffic, and that in turn may be a major inconvenience to the airport operator as well as to the airlines which operate j et aircraft into and out of the airport.
These disadvantages are overcome or precluded by the installation of fiberglass jet blast wall structures in keeping with the present invention. These jet blast wall structures exhibit transparency to radar and radio frequency signals; and while they are relatively lightweight they will withstand jet blasts of departing aircraft. At the same time, jet blast wall structures of the present invention are relatively maintenance free, low cost, and long lasting, so that the capital budgets of airports may be set lower.
Typically, jet blast wall structures in keeping with the present invention are made from fiberglass, in all respects. That is, the major front panel face members of the jet blast wall structure, as well as all of the framing members, and even the nuts and bolts which secure the structure together, are all made from fiberglass. The precise method of fabrication of such panels and framing members, as well as of the nuts and bolts, is well-known to those skilled in the art. However, it is worth noting that the major components are typically either pultruded or molded.
Of course, as is well known to those familiar with fiberglass structures, the placement of such structures outdoors requires the presence of pigment and UV stabilizers incorporated into the resin; and by doing so, the structures are substantially corrosion resistant and maintenance free. It also follows, of course, that by constructing jet blast wall structures in keeping with the present invention substantially entirely from fiberglass, there are no metal parts, and therefore no radio or radar frequency interferences of any sort.
Moreover, the fiberglass jet blast wall structures in keeping with present invention are capable of withstanding jet take off blasts and high winds. In particular, a blast of 160 km/h may be deflected, with a design the Safety Factor of 2:1. However, as noted above, there is sufficient frangibility at selected positions and with respect to selected elements of an installed fiberglass jet blast wall structure that the structure will collapse in the area of impact of an errant jet aircraft with the blast wall. Specifically, as will be noted hereafter, the jet blast wall structure of the present invention is designed with back-to-back edge frame members for the respective panels that comprise the blast deflector, which edge frame members are secured together by nuts and bolts where the bolts have a predetermined shear strength so as to fail at shear forces above that predetermined shear strength.
This designed failure mode of the fiberglass blast wall structures in keeping with the present invention is such that significant damage to an impacting aircraft which might accidentally collide with the blast wall, is precluded.
The fiberglass jet blast wall structures of the present invention are modular in nature, comprising a plurality of panels and support members therefor. Because of the fiberglass material from which the blast wall structures are manufactured, each of the individual elements is relatively lightweight, such that it may be manhandled by construction crew workers without the necessity for the use of cranes and the like. Thus, the presence of cranes—which are necessarily very high with respect to the structure being built—is not necessary, and moreover the presence of large metallic fabrication vehicles is also precluded. Thus, there may be considerably less downtime in respect of the adjacent runway where a fiberglass jet blast wall structure is being built due to avoidance of height restrictions; and no unnecessary interference with radio or radar frequency installations in the immediate area as a consequence of the presence of large construction vehicles.
Another advantage to the utilization of fiberglass jet blast wall structures in keeping with the present invention is their low maintenance. Moreover, because of their smooth surface, snow or other debris are much less likely to collect on the surface of the blast wall. Still further, the jet blast wall structures of the present invention are significantly resistant to corrosion or damage as a consequence of fuel or de-icing chemicals being splashed on them.
The blast wall structures of the present invention are also fire retardant.